Pacific Coral Shows How Global Warming Is Tied to Wind

Scientists studying coral in a western Pacific Ocean lagoon demonstrated that strong trade winds have helped slow global warming for the past 14 years.

As they stir up the sea floor, the tropical winds are pushing warm air into the ocean, cooling the atmosphere. The Nature Geoscience study published today also shows that air temperatures over the Pacific will rise faster when those winds weaken.

Levels of manganese sediments in the coral samples that coincide with wind intensity allowed researchers to date periods of strong and weak winds back to the late 19th century more accurately.

“This is part of a cycle that happens in the Pacific where winds flip flop between really strong and really weak,” Diane Thompson, a scientist at the National Center for Atmospheric Research and one of the study’s authors, said in a telephone interview. “When the winds are strong in the tropical Pacific, as they are right now, you get more mixing of the heat into the subsurface ocean, which leaves the surface ocean cooler and less heat in the atmosphere.”

Coral can be studied similarly to tree rings, giving researchers more data to help determine significant weather and climate shifts, she said. The Pacific trade winds most recently picked up speed in 2000.

The study doesn’t pinpoint when the next cycle of weaker winds will start to cause temperatures to increase. The cycles typically last two to three decades.

“We aren’t yet able to forecast those year-to-year potential changes, but it’s critical that we’re able to anticipate the rate of future warming,” Thompson said. “Like trees, corals grow in yearly growth spans, so we can use the chemistry of that.”

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